Housing for a fan



FIG. 1 is a right side elevational view of a housing for a fan showing my new design, the left side being a mirror image;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a front elevational view thereof; and

FIG. 4 is a top plan view thereof. 

The ornamental design for a housing for a fan, substantially as shown and described. 